Evaluation of eryptosis in patients with chronic kidney disease

Objective Anemia in patients with chronic kidney disease (CKD) is the result of reduced erythropoietin, disturbed erythropoiesis and decreased lifespan of circulating erythrocytes. Excessive eryptosis or premature suicidal erythrocyte death is characterized by cell shrinkage and phosphatidylserine externalization. This study aimed to explore accelerated eryptosis and accompanying biochemical alterations in CKD patients. Patients and methods A total of 106 CKD patients (59 predialysis [PreD] patients, 26 haemodialysis [HD] patients and 21 peritoneal dialysis [PD] patients) and a control group composed of 29 healthy volunteers were included in this study. Data on superoxide dismutase (SOD) activity (U/mL), annexin-V binding (mean fluorescent intensity, MFI) and intracellular calcium ([Ca2+]i; MFI) as well as the hematologic and biochemical parameters were recorded. Results The [Ca2+]i levels were 3.05 +/- 1.66 MFI, 2.24 +/- 0.99 MFI, 2.38 +/- 0.87 MFI and 1.71 +/- 0.46 MFI in the PreD, HD, PD and control groups, respectively. Other than significantly higher [Ca2+]i levels in the PreD group than in the control group (p < 0.001), no significant difference was noted between study groups in terms of [Ca2+]i. Annexin-V binding was 1.05 +/- 0.99 MFI in PreD group, 1.15 +/- 0.56 MFI in HD group, 1.06 +/- 0.87 MFI in PD group, and 0.88 +/- 0.86 MFI in controls. Annexin-V binding was significantly higher in PreD, HD and PD groups compared with the control group (p < 0.001 for each). SOD activity was 0.07 +/- 0.07 in the PreD group, 0.13 +/- 0.08 in the HD group, 0.14 +/- 0.07 in the PD group, and 0.03 +/- 0.01 in the control group. SOD activity in both HD and PD groups were significantly higher than control and PreD groups (p < 0.001 for each). Lower albumin, higher ferritin, and higher parathormon levels were found to be correlated with eryptosis biomarkers. Patients treated vs. non-treated with calcium channel blockers had significantly lower annexin-V binding levels (p = 0.013). Patients treated vs. non-treated with erythropoietin (EPO) had elevated annexin-V binding level (p < 0.001) and lower [Ca2+]i (p = 0.014). Conclusion In conclusion, our findings revealed the presence accelerated eryptosis, as a potential contributing factor to development of anemia, in patients with CKD stages 3-5D. Inflamation and parathormon can also accelerate eryptosis. Favorable effect of CCB and EPO on eryptosis needs to be confirmed in larger scale studies.